Dead Reckoning

Part of Navigation Without Technology

Dead reckoning is the oldest method of tracking your position while moving. You start from a known point, hold a direction, count your paces, and calculate where you are. No instruments required — just discipline. Every army, every sailing expedition, every overland trek in history relied on dead reckoning when maps ran out and landmarks disappeared.

What Dead Reckoning Actually Is

Dead reckoning (from “deduced reckoning”) means calculating your current position based on three inputs:

1. Starting point — a known location (your camp, a river crossing, a hilltop)
2. Direction of travel — the bearing you are holding
3. Distance traveled — measured by pace counting, time, or terrain estimation

You combine these continuously. After walking 800 paces northeast from the river fork, you know approximately where you are — even if you cannot see a single landmark. Dead reckoning is not precise. Errors accumulate with every step. But it is the difference between “roughly there” and “completely lost.”

The Core Method

Step 1: Establish Your Starting Point

Before you move, fix your position. This might be:

• A recognizable terrain feature (hilltop, stream junction, large boulder)
• A camp you have marked with cairns
• A point where you took a compass or sun bearing

If you have any way to record information (scratch on bark, charcoal on stone, scratches in dirt), note what you observe from this point — what is visible, what direction key features lie in.

Step 2: Set Your Bearing

You need a direction to hold. Use any method available:

Method	Accuracy	Conditions Required
Sun position (morning/afternoon)	Rough (15-30 degrees)	Daytime, any weather with visible sun
Shadow stick	Good (5-15 degrees)	Daytime, 15+ minutes of sun
Polaris / Southern Cross	Good (2-5 degrees)	Night, clear sky
Improvised compass	Good (5-10 degrees)	Steel needle, still water
Distant landmark	Excellent (1-2 degrees)	Visible feature on bearing

The best method: pick a distant landmark on your bearing and walk toward it. When you reach it, pick another. This prevents drift far better than trying to hold a mental heading.

Step 3: Hold Your Direction

This is where most people fail. Humans cannot walk straight without a reference point. Studies have shown that blindfolded people walk in circles within minutes — and even sighted people in featureless terrain (fog, dense forest, flat grassland) drift significantly.

Direction-holding techniques:

• Leapfrog landmarks. Pick a tree, rock, or feature directly on your bearing 50-200 meters ahead. Walk to it. Stop. Pick the next one. Repeat. Never walk between landmarks — always have one targeted.
• Back-bearing checks. Every few hundred paces, turn around and look at where you came from. The line from where you are to where you were should be exactly opposite your direction of travel. If it is not, you have drifted. Correct.
• Shadow alignment. If the sun is out, note the angle of your shadow relative to your body at the start. Check it periodically. If it has changed and significant time has not passed, you have turned.
• Wind as a reference. If wind direction is steady, note where it hits your body (left cheek, right ear, back of neck). Maintain that angle. Wind shifts, so check it against your bearing every 15-20 minutes.

The Dominant-Side Drift

Without a fixed reference, right-handed people tend to drift right (clockwise) and left-handed people drift left. This is caused by a slight difference in stride length between your dominant and non-dominant legs. Over 1 km of travel, this drift can push you 50-100 meters off course. Always use landmarks.

Step 4: Count Your Paces

See the detailed Pace Counting guide for full technique. The short version:

• Count every time your left foot (or right foot — pick one) hits the ground
• On flat ground, most adults cover about 60-70 cm per pace (roughly 1,300-1,500 paces per kilometer)
• Calibrate your own pace count over a known distance before you need it
• Use beads, knots, or pebble-transfer systems to track hundreds of paces without losing count

Step 5: Record Your Route

Dead reckoning is useless if you forget what you did. After each leg of travel, record:

• Bearing (direction — “toward the notched peak,” “northeast by shadow stick”)
• Pace count (distance — “420 paces”)
• Terrain notes (“crossed dry streambed,” “entered pine forest”)

Record on any available surface. Charcoal on birch bark. Scratches on a flat stone carried in your pocket. Knots in a cord (one knot per leg, with bead-counting for paces). If you have nothing to write with, use a mnemonic chain — verbally rehearse each leg as you add the next one.

Correcting for Terrain

Dead reckoning on flat ground is straightforward. Real terrain introduces errors that must be compensated for.

Slope Corrections

Walking uphill or downhill changes your effective pace length:

Terrain	Pace Adjustment	Why
Flat ground	Baseline (no correction)	Normal stride
Gentle uphill (5-15 degrees)	Add 10% more paces per unit distance	Shorter stride going up
Steep uphill (15-30 degrees)	Add 20-30% more paces	Much shorter stride, more effort
Gentle downhill	Subtract 5% paces	Slightly longer stride
Steep downhill	Add 10% paces	Short, cautious steps
Thick vegetation	Add 15-25% paces	Weaving, stepping over obstacles
Snow or sand	Add 20-30% paces	Shorter stride, sinking

Detour Handling

When you cannot walk a straight line (cliff, dense thicket, lake), you must detour and return to your original bearing:

The Box Detour:

1. Turn 90 degrees right from your bearing
2. Walk a counted number of paces to clear the obstacle
3. Turn 90 degrees left (back to your original bearing)
4. Walk past the obstacle
5. Turn 90 degrees left again
6. Walk the same number of paces you walked in step 2
7. Turn 90 degrees right — you are back on your original bearing

This creates a rectangular detour around the obstacle. The key: steps 2 and 6 must have the same pace count. Your distance traveled along the bearing is the length of step 4 only.

The 60-Degree Detour (for obstacles you can see around):

1. Turn 60 degrees away from the obstacle
2. Walk until you are past it, counting paces
3. Turn 120 degrees (back across your original line)
4. Walk the same number of paces
5. Turn 60 degrees back to your original bearing

This creates an equilateral triangle. You end up on your original line of travel, having added zero extra distance to your bearing calculation.

Error Budget: How Wrong Will You Be?

Dead reckoning accumulates error. Every source of error compounds over distance.

Source	Typical Error per km	Over 5 km
Pace counting (flat, practiced)	2-5% of distance	100-250 m
Pace counting (rough terrain)	10-15% of distance	500-750 m
Direction drift (with landmarks)	2-3 degrees	175-260 m lateral
Direction drift (no landmarks)	5-15 degrees	435-1,300 m lateral
Combined (good conditions)	—	200-400 m off target
Combined (poor conditions)	—	500-1,500 m off target

After 5 km of careful dead reckoning, expect to be 200-500 meters from your calculated position. After 10 km, 500-1,000 meters. This is why dead reckoning is always combined with:

• Terrain association — matching what you see to what you expected
• Catching features — linear features (roads, rivers, ridgelines) that you will hit regardless of small errors
• Corrective fixes — using the sun, stars, or known landmarks to reset your position periodically

Aiming Off

This is the single most important dead reckoning technique for reaching a specific point on a linear feature (a bridge on a river, a cabin on a road).

The problem: If you aim directly at the target and drift slightly, you will hit the river — but you will not know whether the bridge is to your left or right.

The solution: Deliberately aim to one side. If you aim 5-10 degrees to the left of the bridge, when you hit the river, you know with certainty that the bridge is to your right. Turn right and follow the river until you find it.

This works for any target on a linear feature: a trail junction, a camp on a ridgeline, a ford on a creek.

Night Dead Reckoning

Traveling at night multiplies dead reckoning errors. Visibility is limited, landmarks are hard to identify, and pace length changes on unseen terrain.

If you must travel at night:

1. Use Polaris or the Southern Cross for bearing
2. Pick the closest visible landmark on your bearing — even 20 meters away
3. Walk to it carefully, counting paces
4. Stop. Find the next landmark. Repeat.
5. Accept that your pace count will be less accurate — add 15-20% error margin
6. Stop and rest at any terrain change (drop-off, water, dense brush) until you can assess it

When to Stop

If you cannot see any landmarks at all — total darkness, dense fog, whiteout conditions — stop moving. Dead reckoning without any visual reference is nearly impossible. Shelter in place and resume when visibility returns. Moving blind wastes energy and can walk you off a cliff.

Key Takeaways

• Dead reckoning = known start + direction + distance. All three are required. Missing any one makes the method useless.
• Landmarks are everything. The leapfrog technique (pick a landmark, walk to it, pick the next) eliminates most direction-holding errors.
• Errors accumulate relentlessly. After 5 km, expect to be 200-500 m off in good conditions, much more in bad. Reset your position at every opportunity.
• Aim off on purpose. When targeting a point on a linear feature, deliberately offset your bearing so you know which way to turn when you reach the feature.
• The box detour lets you navigate around obstacles without losing your bearing. Equal pace counts on the offset legs are critical.
• Record every leg. Direction, pace count, terrain notes. If you cannot write, use a mnemonic chain or knotted cord. Memory alone will fail you after 4-5 legs.
• Practice before you need it. Walk a known route using dead reckoning alone. Compare your calculated position to reality. Calibrate your pace count and learn your personal drift tendency.